With increasing consciousness of environmental protection and energy saving, low pressure insulating glasses are widely used for the improvement of thermal and acoustic insulation of doors and windows. The effect of thermal insulation and acoustic insulation is determined by the thickness of the air layer between two flat glasses of the low pressure insulating glass. The thicker the air layer, the better the thermal and acoustic insulation effect. However, the increase of the thickness of the air layer results in high thickness of doors and windows, and thus increases the manufacturing costs. Other methods, such as film plating, film coating, and inert gas filling, are feasible in some extent, but also have high costs.
A typical low pressure insulating glass includes two or more pieces of glasses separated by a partition frame having a drier, and the peripheries of the two or more glasses are sealed by an organic sealant. The organic sealant itself has moisture, poor antiaging capacity, and weak airtightness, thereby affecting the service life of the low pressure insulating glass.
The air in the air layer is sealed between two glasses. When external temperature changes, the pressure of the air layer changes accordingly. When the external temperature rises, the pressure of the air layer is greater than atmospheric pressure, and the glasses of the low pressure insulating glass protrude outwards. When the external temperature falls, the pressure of the air layer is less than atmospheric pressure, and the glasses of the low pressure insulating glass depress inwards. The “breath” of the low pressure insulating glass shortens the service life thereof.
In general, existing methods for preparing vacuum glasses include sealing edges at high temperature, vacuumizing, and sealing the extraction opening. The vacuumizing and sealing the extraction opening are often carried out only on one glass.
The melting temperature of low temperature glass solders of conventional vacuum glass are generally greater than or equal to 400° C. Heating glass at this temperature for a long time will anneal the toughened glass. So, it is very difficult to produce toughened vacuum glass using conventional production technologies.